The present invention relates to the art of manufacturing and, more particularly, to a system for analyzing process steps of a production process.
During production, certain process or tools may have an impact on product quality and yield. That is, many manufactured goods rely on a series of carefully designed process steps utilizing one or more tools. During fabrication, it is critical to identify which tools and/or process steps have a negative impact on product performance. Presently, tools are analyzed using an analysis of variance (ANOVA) model. The ANOVA model ranks processes having significant tool-to-tool differences. While effective, ANOVA cannot identify a tool within a process that has a very large variance or a significantly different mean that hides signals for other tools in the process. In addition, often times a problem with one tool will mask problems in other associated processes. That is, a tool having a high variance or mean shift might mask a tool having a lower variance or mean shift in another process. The ANOVA method cannot identify tools that contribute to product variance or other production parameters in other processes.